In an optical communication system, an optical module used for transmitting and receiving an optical signal is mounted. Such optical module transmits and receives the optical signals of various wavelengths that are modulated by using various modulation schemes (e.g. QPSK [Quadrature Phase Shift Keying], 16QAM [Quadrature Amplitude Modulation], or another scheme) and multiplexed by using various schemes. Some examples of such optical modules have been already proposed.
For example, an optical communication apparatus for eliminating wavelength dependency of the optical signal has been proposed (Patent Literature 1). The optical communication apparatus controls output amplitude of a drive signal provided to an optical modulator so as to realize specified characteristics of the optical modulator according to a wavelength of the optical signal.
Meanwhile, implementing a pluggable optical module in the optical communication system that conforms to a standard such as SFP (Small Form-factor Pluggable) and XFP (10-gigabit small Form-factor Pluggable) is progressing. The pluggable optical module is a transceiver that is insertable into and removable from a socket of the optical communication apparatus (e.g. Patent Literatures 2 and 3). When the pluggable optical module is controlled, the pluggable optical module receives control information from the host side optical communication apparatus. An operation of the pluggable optical module is switched or changed in response to the received information.